One of his teammates was Brady Murray, who would briefly play in the NHL for the Los Angeles Kings,[1] and his linemate was future Calgary Flames winger Kris Chucko.

[2] In his second season with Salmon Arm, Zajac led the team in goals, assists and points,[1] and finished second overall in the League in the latter two statistics.

[8] Then-Devils General Manager Lou Lamoriello commented that there would be room for Zajac on the North Dakota roster because the Devils were recalling forward Zach Parise, drafted the year earlier, to play professional hockey.

[7] In his first season with North Dakota, Zajac scored 17 goals and 19 assists for 36 points, while only accumulating 16 penalty minutes.

The Fighting Sioux, as the team's nickname was then known, advanced to the 2005 NCAA Division I Men's Ice Hockey Tournament as the second seed in the East Regional.

That season, the Sioux featured several future NHL players, including Taylor Chorney, Brian Lee, T. J. Oshie, Chris Porter, Matt Smaby, Drew Stafford and Jonathan Toews.

[12] After defeating the University of Michigan and Holy Cross, the Sioux were in the Frozen Four for the second-straight year, but lost to Boston College in the semifinals.

[18] He scored one assist and earned two penalty minutes in two appearances with the Devils' American Hockey League (AHL) affiliate, the Albany River Rats.

[20] Zajac was placed on the Devils' second line with former North Dakota standout Zach Parise and veteran winger Jamie Langenbrunner.

[20] Midway through the season, to spark the Devils' offense, Zajac and Langenbrunner were placed on a line with then-captain Patrik Eliáš.

[24] Later in the season, Zajac notched his first NHL two-goal game against the Philadelphia Flyers, and had an eight-game point streak in late March.

[13][20] In the 2007 Stanley Cup playoffs, Zajac scored his first career NHL post-season point with an assist in Game 3 of the Eastern Conference Quarterfinals against the Tampa Bay Lightning.

[29] At the start of Zajac's sophomore season, he was still centering the second line with Zach Parise;[30] Brian Gionta replaced Langenbrunner on right wing while the latter recovered from sports hernia surgery.

[32] In October, he was moved up to the top line, centering Gionta and Eliáš, and saw an increase in time on the power play unit.

[33] January 2008 was a good month for Zajac – he had a four-game point streak, during which he tied his career high with a three-point game (three assists) against the Flyers.

[40] Further injuries and poor play forced Head Coach John MacLean to shuffle his lines further; Zajac's linemates for the first half of the season included Parise, Langenbrunner,[41] Kovalchuk, Zubrus, Brian Rolston, David Clarkson,[42] Eliáš and Adam Mair.

[44] Following the firing of MacLean and the trading of captain Langenbrunner, the Devils found themselves playing better under returning Head Coach Jacques Lemaire.

[45] Zajac snapped a five-game pointless streak, and shortly thereafter scored a short-handed goal and added three assists in just three games.

[45] Finding consistency on a line with Kovalchuk and rookie Nick Palmieri, his offense improved; during a 20-game streak, he scored five goals and added 11 assists.

[64] In 2009, Zajac married former captain of the University of New Hampshire women's ice hockey team Nicole Hekle.